<style>
    .box {
        display: flex;
        justify-content: flex-start;
        width: 300px;
        border: 1px solid #aaa;
        border-radius: 5px;
        box-shadow: 2px 2px 8px rgba(0,0,0,0.1);
        padding: 1em;
        margin: 0 1em 1em 1em;
    }
</style>

<div class="box">
    <slot></slot>
</div>